1. Field of the Invention
The invention relates generally to a self-opening pocket umbrella of the topless type, i.e. in which the cover is not directly supported by the canopy framework immediately around the top of the stick.
These umbrellas are of the type having a telescopic stick and a collapsible canopy framework extending radially from the stick in the form of scissor-link folding systems which can be spread by means of an opening spring and collapsed manually by a slider which is displaceable along the stick. Each scissor-link folding system having a pair of scissor levers, of which an upper one of the scissor levers is pivotally linked to a main crown, while the lower one of the scissor levers is pivotally connected to the slider. Such an umbrella is hereinafter referred to as of the kind described.
2. Description of Related Art
Umbrellas of this kind are known, for example, from U.S. Pat. No. 4,682,617. As a result of the scissor-operated folding kinematics of the canopy framework, they are stable in their design and very user-friendly since they can be opened and closed in one movement by the operation of the slider, involving simultaneous, automatic folding up of the canopy cover. In contrast, it is disadvantageous that the opening spring stressed between the slider and an associated auxiliary slider in the known frames of this type, and their encapsulation take up appreciable space between the telescopic stick and the canopy framework so that the known umbrellas of this type become relatively thick in cross-section in the closed state. Additionally, the opening spring in this design rubs up and down over virtually the entire length of the stick when the umbrella is opened and closed with the result that wear-scratches on the stick cannot be avoided.
Moreover, this arrangement and function of the opening spring, together with the tensioning and sliding mechanism between the auxiliary and main sliders moving the lever scissors, requires a relatively large spring force and thus also a great manual effort upon closing, making the closing movement somewhat difficult.